Metal truck axle tubes and similar types of steel tubular members have been manufactured in the past by either forging processes, machining processes or by cold forming processes such as disclosed in my prior U.S. Pat. No. 3,837,205 issued Sept. 24, 1974 or U.S. Pat. No. 3,886,649 issued June 3, 1975. These processes generally involve the production of a finished tube, having varying thickness wall sections, out of separate tube parts which are welded or otherwise secured together. Further, where the tube includes some thick wall sections along with some thin wall sections, manufacturing this kind of tube has been difficult and time consuming.
Thus, a cold forming process of the type disclosed in my above mentioned patents, is utilized in the present invention, with certain modifications and improvements, to thereby produce a one-piece, multiple thickness wall section tube which may be used as a truck axle tube or for other similar tube purposes. Particularly, the extrusion of such tubes, using a cold forming extrusion process lends itself to rapid production with relatively low cost and particularly to the opportunity to reduce weight by utilizing thin wall sections where possible while still producing the thicker wall sections needed for machining purposes, bearing supports, etc.
Thus, the invention herein relates to a cold forming or extrusion process for producing, in one die operation, a finished, elongated steel or the like metal tube which is essentially of thin wall cross-section, but is provided with thickened wall sections in areas desired.